Reports of more than one blast on the Tube. At least one double decker bus has been blown up - removing the top deck in the explosion.
It has been confirmed that there have been at least six explosions. There are unconfirmed reports of explosions on a bus in South Kensington and elsewhere.
Eyewitness reports are difficult to interpret. Lots of people (esp at Liverpool Street) report being walked past the carriages that had been damaged by explosion to get to the platforms.
Other reports seem to track with the "powersurge" thing - lights flickering before explosions at platforms.
Certainly people have been killed - BBC footage of the Royal London hospital showed an ambulance crew desperately working on a burned man - it seemed like they'd broken his ribs trying to keep his heart beating. Terrible.
Tony Blair has made a statement confirming that he will be returning to London shortly and that the G8 conference will continue. He believed that it had been a terroist incident.
London cell networks seem to have fallen over - or at least have reached maximum capacity - so I'd stick to txt messages but call only if absolutely necessary.
Latest 12.29 - now confirming seven explosions - including Moorgate tube (I think).
Comment on BBC News site suggests that there had been a security alert at Bank station before the Aldgate incident.